CN113871120A - Mixed rare earth permanent magnetic material and preparation method thereof - Google Patents
Mixed rare earth permanent magnetic material and preparation method thereof Download PDFInfo
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- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
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- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
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- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
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- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/0293—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
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Abstract
The invention discloses a mixed rare earth permanent magnetic material and a preparation method thereof, belonging to the field of magnetic materials. The chemical expression of the mixed rare earth permanent magnetic material in percentage by mass is MMaRbMcFedBCeOHfThe rare earth alloy is prepared by using a Ce-based mixed rare earth alloy MM with La, Ce, Pr and Nd as main components and one or more rare earth metals R selected from Y, La, Ce, Pr, Nd, Gd, Tb, Dy and Ho as rare earth raw materials through the processes of proportioning, alloying, hydrogen breaking, grinding by an oxygen-adding jet mill, molding, sintering, tempering and the like. The invention gives consideration to the requirements of fully utilizing the mixed rare earth and obtaining good magnetic property, and is beneficial to the energy-saving, environment-friendly and efficient application of the high-abundance rare earth La and Ce in the rare earth permanent magnet material.
Description
Technical Field
The invention belongs to the technical field of magnetic materials, and particularly relates to a mixed rare earth permanent magnet material prepared from a Ce-based mixed rare earth alloy MM and a preparation method thereof.
Background
The rare earth permanent magnetic material is one of the most important applications of rare earth in the field of new materials, and the rare earth used for preparing the rare earth permanent magnetic material accounts for more than 40 percent of the total consumption of the rare earth every year. Of these, praseodymium-neodymium metal is most used.
In nature, the rare earth lanthanum La and the rare earth Ce both belong to high-abundance rare earth, and the sum of the rare earth lanthanum La and the rare earth Ce accounts for more than 58 percent of the total amount of the rare earth. In particular, in Baotobaiyuneboite in China, La and Ce account for more than 75% of the total amount of rare earth.
How to effectively utilize La and Ce in rare earth permanent magnetic materials has become a research hotspot in the field of permanent magnetic materials at home and abroad in recent years. The Chinese patent of the invention discloses a low-cost double-main-phase Ce permanent magnet alloy and a preparation method thereof (Chinese patent application No.201210315684.5, application date 2012.8.30), and a patentee-iron and steel research institute utilizes the double-main-phase technology to develop a rare earth permanent magnet material containing Ce with practical value and market competitiveness, thereby realizing the high-efficiency utilization of high-abundance rare earth Ce.
The method for preparing the rare earth permanent magnet material by directly utilizing the Ce-based mixed rare earth metal MM can reduce the processes of rare earth separation and purification, is beneficial to environmental protection, energy conservation and cost reduction, can directly utilize the high-abundance rare earth La and Ce according to the original proportion in the original ore, and has important significance for realizing the balanced utilization of rare earth elements and the sustainable development of the rare earth permanent magnet material.
Disclosure of Invention
In view of the above analysis, the invention aims to provide a mischmetal permanent magnet material prepared by directly utilizing a Ce-based mischmetal MM and a preparation method thereof, so as to realize energy-saving, environment-friendly and efficient utilization of abundant rare earth La and Ce.
The purpose of the invention is mainly realized by the following technical scheme:
the invention provides a mixed rare earth permanent magnet material, which directly uses a Ce-based mixed rare earth alloy as a raw material, and comprises the following components in percentage by mass: MM (Measure and Regulation)aRbMcFedBCeOHfWherein, MM is Ce-based mixed rare earth alloy taking La, Ce, Pr and Nd as main rare earth elements; r is selected from Y, La,Ce. One or more of rare earth metals of Pr, Nd, Gd, Tb, Dy and Ho, M is one or more of metals selected from Al, Ti, V, Cr, Cu, Co, Ga, Nb, Zr, Mo, W, Mn and Ni, BC represents B or the combination of B and a small amount of C, OH represents O or the combination of O and H; wherein a, b, c, d, e and f are the mass percentages of the components, a is more than or equal to 3 and less than or equal to 30, b is more than or equal to 3 and less than or equal to 30, c is more than or equal to 0.02 and less than or equal to 10, d is more than or equal to 55 and less than or equal to 70, e is more than or equal to 0.9 and less than or equal to 1.2, and f is more than or equal to 0.02 and less than or equal to 0.5.
Furthermore, in the mixed rare earth permanent magnet material, the MM directly uses Ce-based mixed rare earth alloy; r is pure rare earth alloy with the purity of more than 99 percent, or rare earth alloy containing more than two rare earths or rare earth-iron alloy; m is pure metal or alloy with Fe; b in BC is ferroboron.
Furthermore, a is more than or equal to 3.2 and less than or equal to 20, b is more than or equal to 10 and less than or equal to 28.8, c is more than or equal to 0.1 and less than or equal to 5, and e is more than or equal to 0.95 and less than or equal to 1.05.
Furthermore, a is more than or equal to 3.2 and less than or equal to 10, b is more than or equal to 18 and less than or equal to 28.8, c is more than or equal to 0.1 and less than or equal to 5, and e is more than or equal to 0.98 and less than or equal to 1.05.
Further, R is selected from more than two of rare earth metals of Y, La, Ce, Pr, Nd, Gd, Tb, Dy and Ho.
Further, R is selected from more than two of rare earth metals of Y, La, Ce, Pr, Nd, Gd, Dy and Ho.
Further, the MM comprises the following main components in percentage by mass: la: 20% -30%, Pr: 4% -10%, Nd: 12 to 30 percent of the total weight of the alloy, less than or equal to 2 percent of other elements and inevitable impurities, and the balance of Ce.
Further, when R is mainly Nd or Pr + Nd, the Nd or Pr + Nd accounts for more than 50% of the R in mass percentage;
when R is mainly Nd + Ce or Pr + Nd + Ce, the Nd + Ce or Pr + Nd + Ce accounts for more than 50% of R in mass percent;
when R is mainly Nd + Gd or Pr + Nd + Gd, the Nd + Gd or Pr + Nd + Gd accounts for more than 50 percent of the R in mass percent.
Further, in the M, the proportion of the mixed rare earth permanent magnet material is as follows by mass percent: al: 0-3, Cu: 0-0.5, Co: 0-6, Nb: 0 to 0.3, Zr: 0-0.3, Ga: 0-0.3.
Further, in the M, the proportion of the mixed rare earth permanent magnet material is as follows by mass percent: al: 0.3-3, Cu: 0.2-0.5, Co: 0.15-6, Nb: 0.1-0.3, Zr: 0.15-0.3, Ga: 0.1-0.3.
Further, in the M, the proportion of the mixed rare earth permanent magnet material is as follows by mass percent: the ranges of Ti, V, Cr, Mo, W, Mn and Ni are all 0-0.3, and the total of the components is less than 0.5.
Further, the B accounts for more than 85% of the BC according to the mass percentage.
Further, the proportion of O in the mixed rare earth permanent magnet material is not less than 0.02 in percentage by mass.
Further, the magnetism of the mixed rare earth permanent magnetic material is as follows: residual magnetism Br: 6-14.5kGs, Hcj: 4-25kOe, maximum energy product (BH) m: 8-52 MGOe.
On the other hand, the invention also provides a preparation method of the mixed rare earth permanent magnetic material, which comprises the following steps:
(1) preparing materials: weighing and batching different elements according to material components, wherein:
the MM directly uses Ce-based mixed rare earth alloy; r is pure rare earth alloy with the purity of more than 99 percent, rare earth alloy containing more than two rare earths or rare earth-iron alloy; m is pure metal or alloy with Fe; b in BC is ferroboron;
(2) alloying: preparing the prepared raw materials into a rapid hardening sheet alloy through a smelting-rapid hardening process or preparing an ingot casting alloy through a smelting-casting process;
(3) crushing: for the quick-setting slices, crushing is directly carried out by using a hydrogen crushing and airflow milling process; for the ingot casting alloy, firstly carrying out rough crushing, then crushing by using a hydrogen crushing and airflow milling process, and crushing the ingot casting alloy into particles; wherein, the hydrogen residual content of the powder after hydrogen breaking is 0.001 to 0.1 percent; after the jet milling process, the oxygen content of the final powder component is 0.01-0.2%;
(4) molding: placing the crushed alloy powder into a die, pressing and molding in a magnetic field of more than 1.5T, and further densifying by cold isostatic pressing to prepare the alloy powder with the density of 3.5-4.5g/cm3A green compact of (1);
(5) and (3) sintering: putting the pressed compact into a metal or graphite material box, and then putting the pressed compact into a sintering furnace to be sintered into a high-density sintered blank; sintering temperature: 1020 ℃ and 1120 ℃, sintering time: 2-5 hours, and before the sintering temperature is reached, the process of temperature rise and heat preservation is carried out in sections;
(6) tempering: performing primary or secondary tempering on the sintered blank to prepare a mixed rare earth permanent magnet material with optimized microstructure;
the smelting-rapid hardening process in the step (2) is characterized in that the prepared raw materials are placed in a crucible, fully smelted in a vacuum frequency induction furnace, argon gas with certain pressure is filled in the furnace, then molten metal liquid is poured onto the surface of a rotating water-cooling copper roller through a tundish, the linear speed of the surface of the copper roller is controlled to be 1-3m/s, and the molten liquid is rapidly thrown out of the copper roller to form a rapid hardening sheet with the thickness of 0.1-0.6 mm;
the hydrogen breaking and air flow grinding process in the step (3) is that quick-setting slices or rough-broken cast ingots are put into a material box in a hydrogen breaking furnace or directly put into a rotary hydrogen breaking furnace, and are broken into coarse powder with the average particle size of less than 0.5mm through the processes of hydrogen absorption and hydrogen desorption, and then the coarse powder is further broken into fine powder with the average particle size of 2 to 5 mu m in air flow grinding equipment; wherein, the air flow milling process is to fill nitrogen, argon or helium with controlled oxygen content in a certain proportion into a working medium of the air flow milling equipment, and the preferred oxygen content is 20-80 ppm.
Further, in the (6),
when the secondary tempering process is adopted, the primary tempering temperature is 850-600 ℃, and 930 ℃ and the secondary tempering temperature is 400-930 ℃;
when the primary tempering process is adopted, the tempering temperature is 400-650 ℃.
Compared with the prior art, the invention can realize at least one of the following beneficial effects:
the invention gives consideration to the requirements of fully utilizing the mixed rare earth and obtaining good magnetic performance, and is beneficial to the energy-saving, environment-friendly and efficient application of the high-abundance rare earth La and Ce in the mixed rare earth permanent magnet material.
Detailed Description
The following describes in further detail embodiments of the present invention.
The invention provides a mixed rare earth permanent magnetic material, which comprises the following components in percentage by mass: MM (Measure and Regulation)aRbMcFedBCeOHfWherein MM is a mixed rare earth alloy taking La, Ce, Pr and Nd as main rare earth elements, R represents one or a combination of more of rare earth metals such as Y, La, Ce, Pr, Nd, Gd, Tb, Dy and Ho, M represents one or a combination of more of metals such as Al, Ti, V, Cr, Cu, Co, Ga, Nb, Zr, Mo, W, Mn and Ni, BC represents a combination of B or B and a small amount of C, and OH represents O or a combination of O and H; wherein a is more than or equal to 3 and less than or equal to 30, b is more than or equal to 3 and less than or equal to 30, c is more than or equal to 0.02 and less than or equal to 10, d is more than or equal to 55 and less than or equal to 70, e is more than or equal to 0.9 and less than or equal to 1.2, and f is more than or equal to 0.02 and less than or equal to 0.5.
The mixed rare earth alloy MM comprises the following main components in percentage by mass: la: 20-30, Ce: 45-60, Pr: 4-10, Nd: 12 to 30 percent, and less than or equal to 2 percent of other elements and inevitable impurities.
One of the preferable rare earth metals R is mainly Nd or Pr and Nd, and the Nd or Pr and Nd accounts for more than 50 percent of the R in mass percentage.
In order to further utilize the high-abundance rare earth, the other rare earth metal R preferably takes Nd + Ce or Pr + Nd + Ce as the main component, and the Nd + Ce or Pr + Nd + Ce accounts for more than 50 percent of the R in mass percentage content.
In order to reduce the cost and keep higher magnetic performance, the other preferable rare earth metal R is mainly Nd + Gd or Pr + Nd + Gd, and the Nd + Gd or Pr + Nd + Gd accounts for more than 50 percent of the R in mass percentage.
For part of metals M, the preferred proportion of the metals M in the mixed rare earth permanent magnet material is respectively as follows by mass percent: al: 0-3, Cu: 0-0.5, Co: 0-6, Nb: 0 to 0.3, Zr: 0-0.3, Ga: 0-0.3.
For the other metal M, the preferred proportion of the mixed rare earth permanent magnetic material calculated by mass percent is respectively as follows: the ranges of Ti, V, Cr, Mo, W, Mn and Ni are all 0-0.3, and the total of the components is less than 0.5.
The BC may contain a small amount of C, but it is ensured that B accounts for more than 85% of BC.
In order to obtain good and stable magnetic performance, the mixed rare earth permanent magnet material contains a small amount of O, and the percentage of O in the mixed rare earth permanent magnet material is not less than 0.02 by mass.
The mixed rare earth permanent magnet material meets different cost and performance requirements, and the magnetic performance meets the following requirements: residual magnetism Br: 6-14.5kGs, intrinsic coercivity Hcj: 4-25kOe, maximum energy product (BH) m: 8-52 MGOe.
The preparation method of the mixed rare earth permanent magnetic material comprises the following steps:
(1) preparing materials: weighing and proportioning different elements according to a certain proportion. In the raw materials, MM directly uses Ce-based mixed rare earth alloy, R uses pure rare earth alloy with the purity of more than 99 percent, or rare earth alloy containing more than two rare earths, or rare earth-iron alloy, M uses pure metal or alloy with Fe, B uses ferroboron alloy in BC, C uses ferrocarbon or graphitic carbon, and O and H are not added in the ingredients.
(2) Alloying: different elements are prepared into rapid hardening sheet alloy through a smelting-rapid hardening process or are prepared into ingot alloy through a smelting-casting process.
(3) Crushing: for the quick-setting slices, the hydrogen breaking and airflow milling processes can be directly utilized for breaking; for the ingot casting alloy, the ingot casting alloy can be roughly broken, then the ingot casting alloy is broken by utilizing the hydrogen breaking and airflow milling process, and the ingot casting alloy is broken into particles of 2-5 microns. Wherein, partial hydrogen is allowed to remain after hydrogen breaking (the content is not higher than 0.1%); during the air flow milling, the atmosphere of the milling chamber should contain a certain amount of oxygen, so that the content of oxygen in the final powder component is between 0.01 and 0.2 percent.
(4) Molding: placing the crushed alloy powder into a die, pressing and molding in a magnetic field of more than 1.5T, and further densifying by cold isostatic pressing to prepare the alloy powder with the density of 3.5-4.5g/cm3The green compact of (4).
(5) And (3) sintering: and placing the pressed compact into a metal or graphite material box, and then placing the pressed compact into a sintering furnace to be sintered under a certain sintering process condition to prepare a high-density sintered blank.
(6) Tempering: and performing primary or secondary tempering on the sintered blank to prepare the mixed rare earth permanent magnet material with optimized microstructure.
In the step (2), the smelting-rapid hardening process is that the prepared raw materials containing mixed rare earth are placed in a crucible, argon with certain pressure is filled in a vacuum frequency induction furnace after the raw materials are fully smelted, then molten metal liquid is poured onto the surface of a rotating water-cooling copper roller through a tundish, the linear speed of the surface of the copper roller is controlled to be 1-3m/s, the molten liquid is rapidly thrown out of the copper roller, and a rapid hardening sheet with the thickness of 0.1-0.6mm is formed; preferably, the average thickness is 0.25 to 0.4 mm.
In the step (3), the hydrogen breaking and airflow milling process is that quick-setting slices or rough-broken cast ingots are put into a material box in a hydrogen breaking furnace or directly put into a rotary hydrogen breaking furnace, and are broken into coarse powder with the average particle size of less than 0.5mm through the processes of hydrogen absorption and hydrogen desorption, and then the coarse powder is further broken into fine powder with the average particle size of 2 to 5 mu m in airflow milling equipment; preferably, the average particle size is 2.5 to 4 μm.
The jet milling process refers to that the working medium in the jet milling equipment is nitrogen, argon or helium with controlled oxygen content in a certain proportion, and the preferred oxygen content proportion is 20-80 ppm.
In the step (5), for different component ratios, the sintering process conditions are preferably as follows: sintering temperature: 1020 ℃ and 1120 ℃, sintering time: 2-5 hours, and before the sintering temperature is reached, the process of temperature rise and heat preservation is carried out in sections.
In the step (6), when the secondary tempering process is adopted, the primary tempering temperature is preferably 850-.
In the step (6), when only the primary tempering process is adopted, the tempering temperature is preferably 400-650 ℃.
Example 1
Preparing materials:
the raw material is Ce-based mixed rare earth alloy MM, and the rare earth alloy comprises the following components in percentage by weight: 50 wt% Ce, 27.06 wt% La, 5.22 wt% Pr, 16.16 wt% Nd, Pr-Nd alloy with purity greater than 99.525Nd75And pure metals of iron, cobalt, aluminum and copper, wherein boron and niobium are added in the form of ferroboron and ferroniobium alloy, and the mass ratio is shown in Table 1:
table 1 example 1 the mass percentages of the components
| Composition (I) | MM | PrNd | B | Co | Cu | Nb | Al | Fe |
| Example 1 (wt%) | 3.2 | 28.8 | 0.98 | 0.15 | 0.2 | 0.10 | 0.3 | Remainder of |
During the batching, firstly, oxide scales on the surfaces of raw materials are removed, and then, the weights of the raw materials are weighed by an electronic balance according to the nominal composition of the alloy.
Strip casting alloying: vacuum intermediate frequency induction melting and a rapid hardening process are adopted to prepare the rapid hardening sheet. Firstly, putting the prepared raw materials into a clean crucible, then carrying out vacuum melting in a medium-frequency induction melting furnace, casting molten metal onto a rotating water-cooled copper roller through a tundish after melting, wherein the surface linear velocity of the copper roller is 1.5m/s, and obtaining a quick-setting sheet with the thickness of 0.23-0.45 mm;
hydrogen breaking: carrying out hydrogen crushing treatment on the quick-setting strip by adopting a rotary hydrogen crushing furnace, and coarsely crushing the quick-setting sheet into particles with the particle size of less than 0.5 mm;
milling powder by airflow: carrying out jet milling under 0.7MPa by using inert gases such as high-pressure nitrogen and the like, supplementing 20ppm of oxygen in the jet milling process, and crushing hydrogen into fine powder with the average particle size of 3.5 mu m;
magnetic field orientation molding: the magnetic powder is oriented and molded under the magnetic field of more than 1.5T, and is made into a green body through cold isostatic pressing at 18MPa, wherein the density of the green body is 4.2g/cm3；
Using a high vacuum sintering furnace at 10-3-10-2Under the condition of Pa, sintering for 4 hours at the temperature of 1100 ℃, then carrying out primary tempering treatment for 3 hours at the temperature of 930 ℃, and carrying out secondary tempering treatment for 3 hours at the temperature of 550 ℃ to obtain the final magnet.
The final magnet was tested for room temperature magnetic properties and hydrogen and oxygen content, and the results are shown in table 2:
TABLE 2 results of room temperature magnetic properties and hydrogen and oxygen content testing of example 1
Example 2
Preparing materials:
the raw materials used are mixed rare earth alloy MM (50 wt% Ce, 27.06 wt% La, 5.22 wt% Pr, 16.16 wt% Nd) and praseodymium-neodymium alloy Pr with the purity of more than 99.525Nd75And pure metals of iron, cobalt, aluminum and gallium, wherein boron and niobium are added in the form of ferroboron and ferroniobium alloy, and the weight ratio is shown in Table 3:
table 3 example 2 compositions in mass percent
| Composition (I) | MM | PrNd | B | Co | Ga | Nb | Al | Fe |
| Example 2 (wt%) | 6.4 | 25.6 | 0.98 | 0.15 | 0.1 | 0.10 | 0.3 | Remainder of |
During the batching, firstly, oxide scales on the surfaces of raw materials are removed, and then, the weights of the raw materials are weighed by an electronic balance according to the nominal composition of the alloy.
Strip casting alloying: vacuum intermediate frequency induction melting and a rapid hardening process are adopted to prepare the rapid hardening sheet. Firstly, putting the prepared raw materials into a clean crucible, then carrying out vacuum melting in a medium-frequency induction melting furnace, casting molten metal onto a rotating water-cooled copper roller through a tundish after melting, wherein the surface linear velocity of the copper roller is 2m/s, and obtaining a quick-setting sheet with the thickness of 0.2-0.4 mm;
hydrogen breaking: carrying out hydrogen crushing treatment on the quick-setting strip by adopting a rotary hydrogen crushing furnace, and coarsely crushing the quick-setting sheet into particles with the particle size of less than 0.5 mm;
milling powder by airflow: carrying out jet milling under 0.7MPa by using inert gases such as high-pressure nitrogen and the like, supplementing oxygen by 40ppm in the jet milling process, and crushing hydrogen into fine powder with the average particle size of 3.2 mu m;
magnetic field orientation molding: the magnetic powder is oriented and molded under the magnetic field of more than 1.5T, and is made into a green body through cold isostatic pressing at 18MPa, wherein the density of the green body is 4.0g/cm3；
Using a high vacuum sintering furnace at 10-3-10-2Under Pa, sintering for 4 hours at 1080 ℃, then carrying out primary tempering treatment for 3 hours at 900 ℃, and carrying out secondary tempering treatment for 3 hours at 520 ℃ to obtain the final magnet.
The final magnet was tested for room temperature magnetic properties and hydrogen and oxygen content, and the results are shown in table 4:
TABLE 4 example 2 magnetic Properties at Room temperature and results of hydrogen and oxygen content testing
Example 3
Preparing materials:
the raw materials used are misch metal MM (50 wt% Ce, 27.06 wt% La, 5.22 wt% Pr, 16.16 wt% Nd), Pr25Nd75 of Pr-Nd alloy with purity greater than 99.5 and pure metals of Ce, Gd, Fe, Al and Zr, boron is added in the form of B-Fe alloy, and the weight ratio is shown in Table 5:
table 5 example 3 compositions in weight percent
| Composition (I) | MM | PrNd | Ce | Gd | B | Zr | Al | Fe |
| Example 3 (wt%) | 10 | 18 | 2 | 1 | 1.05 | 0.15 | 2 | Remainder of |
During the batching, firstly, oxide scales on the surfaces of raw materials are removed, and then, the weights of the raw materials are weighed by an electronic balance according to the nominal composition of the alloy.
Alloying of the cast ingot: vacuum intermediate frequency induction melting and ingot casting alloying are adopted, firstly, the prepared raw materials are put into a clean crucible, then the crucible is put into an intermediate frequency induction melting furnace for vacuum melting, and molten metal is cast into a water-cooling clamping plate copper mold through a transition ladle after melting;
rough crushing and hydrogen crushing: crushing the cast ingot into coarse powder with the granularity of below 2mm by using a coarse crusher, and then performing hydrogen crushing treatment on the coarse powder by using a rotary hydrogen crushing furnace to obtain particles with the granularity of below 0.5 mm;
milling powder by airflow: carrying out jet milling under 0.7MPa by using inert gases such as high-pressure nitrogen and the like, supplementing 20ppm of oxygen in the jet milling process, and crushing hydrogen into fine powder with the average particle size of 4.0 mu m;
magnetic field orientation molding: the magnetic powder is oriented and molded under the magnetic field of more than 1.5T, and is made into a green body through cold isostatic pressing at 18MPa, wherein the density of the green body is 4.2g/cm3；
Using a high vacuum sintering furnace at 10-3-10-2Under the condition of Pa, sintering for 4 hours at the temperature of 1150 ℃, then carrying out primary tempering treatment for 3 hours at the temperature of 900 ℃, and carrying out secondary tempering treatment for 3 hours at the temperature of 580 ℃ to obtain the final magnet.
The final magnet was tested for room temperature magnetic properties and hydrogen and oxygen content, and the results are shown in Table 6:
TABLE 6 example 3 magnetic Properties at Room temperature and results of hydrogen and oxygen content test
Example 4
Preparing materials:
the raw materials used are mixed rare earth alloy MM (50 wt% Ce, 27.06 wt% La, 5.22 wt% Pr, 16.16 wt% Nd) and praseodymium-neodymium alloy Pr with the purity of more than 99.525Nd75And pure metals of iron, aluminum and chromium, wherein boron, holmium and dysprosium are added in the form of ferroboron, holmium iron and dysprosium iron alloy, and the weight ratio is shown in Table 7:
table 7 example 4 compositions in weight percent
| Composition (I) | MM | PrNd | B | Ho | Dy | Cr | Al | Fe |
| Example 4 (wt%) | 5 | 22.5 | 1.03 | 3.5 | 0.5 | 0.10 | 0.9 | Remainder of |
During the batching, firstly, oxide scales on the surfaces of raw materials are removed, and then, the weights of the raw materials are weighed by an electronic balance according to the nominal composition of the alloy.
Strip casting alloying: vacuum intermediate frequency induction melting and a rapid hardening process are adopted to prepare the rapid hardening sheet. Firstly, putting the prepared raw materials into a clean crucible, then carrying out vacuum melting in a medium-frequency induction melting furnace, casting molten metal onto a rotating water-cooled copper roller through a tundish after melting, wherein the surface linear velocity of the copper roller is 1.5m/s, and obtaining a quick-setting sheet with the thickness of 0.21-0.44 mm;
hydrogen breaking: carrying out hydrogen crushing treatment on the quick-setting strip by adopting a rotary hydrogen crushing furnace, and coarsely crushing the quick-setting sheet into particles with the particle size of less than 0.5 mm;
milling powder by airflow: carrying out jet milling under 0.7MPa by using inert gases such as high-pressure nitrogen and the like, supplementing oxygen by 50ppm in the jet milling process, and crushing hydrogen into fine powder with the average particle size of 3.2 mu m;
magnetic field orientation molding: the magnetic powder is oriented and molded under the magnetic field of more than 1.5T, and is made into a green body through cold isostatic pressing at 18MPa, wherein the density of the green body is 4.0g/cm3
Using a high vacuum sintering furnace at 10-3-10-2Under the condition of Pa, sintering for 4 hours at the temperature of 1030 ℃, then carrying out primary tempering treatment for 3 hours at the temperature of 890 ℃, and carrying out secondary tempering treatment for 3 hours at the temperature of 490 ℃ to obtain the final magnet.
The final magnet was tested for room temperature magnetic properties and hydrogen and oxygen content, and the results are shown in Table 8:
TABLE 8 example 4 magnetic Properties at Room temperature and results of hydrogen and oxygen content testing
The above examples show that the mixed rare earth permanent magnetic material provided by the invention can show excellent magnetic performance, and the invention has important significance for balanced application of rare earth resources and reduction of production cost of magnetic steel.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications are all within the protection scope of the present invention as claimed.
Claims (10)
1. A mixed rare earth permanent magnetic material is characterized in that,
the mixed rare earth permanent magnet material directly uses a Ce-based mixed rare earth alloy as a raw material, and comprises the following components in percentage by mass: MM (Measure and Regulation)aRbMcFedBCeOHfWherein, MM is Ce-based mixed rare earth alloy taking La, Ce, Pr and Nd as main rare earth elements; r is one or more of rare earth metals selected from Y, La, Ce, Pr, Nd, Gd, Tb, Dy and Ho, M is one or more of metals selected from Al, Ti, V, Cr, Cu, Co, Ga, Nb, Zr, Mo, W, Mn and Ni, BC represents B or the combination of B and a small amount of C, and OH represents O or the combination of O and H; wherein a, b, c, d, e and f are the mass percentages of the components, a is more than or equal to 3 and less than or equal to 30, b is more than or equal to 3 and less than or equal to 30, c is more than or equal to 0.02 and less than or equal to 10, d is more than or equal to 55 and less than or equal to 70, e is more than or equal to 0.9 and less than or equal to 1.2, and f is more than or equal to 0.02 and less than or equal to 0.5.
2. The mixed rare earth permanent magnetic material of claim 1, wherein a is 3.2-20, b is 10-28.8, c is 0.1-5, and e is 0.95-1.05.
3. The mixed rare earth permanent magnetic material of claim 1, wherein R is selected from two or more rare earth metals of Y, La, Ce, Pr, Nd, Gd, Tb, Dy, Ho.
4. The mixed rare earth permanent magnetic material of claim 1, wherein the MM comprises the following main components in percentage by mass: la: 20% -30%, Pr: 4% -10%, Nd: 12 to 30 percent of the total weight of the alloy, less than or equal to 2 percent of other elements and inevitable impurities, and the balance of Ce.
5. The mixed rare earth permanent magnetic material according to claim 1,
when R is mainly Nd or Pr and Nd, the Nd or Pr and Nd accounts for more than 50% of R in mass percentage;
when R is mainly Nd + Ce or Pr + Nd + Ce, the Nd + Ce or Pr + Nd + Ce accounts for more than 50% of R in mass percent;
when R is mainly Nd + Gd or Pr + Nd + Gd, the Nd + Gd or Pr + Nd + Gd accounts for more than 50 percent of the R in mass percent.
6. The mixed rare earth permanent magnet material of claim 1, wherein the ratio of M to the mixed rare earth permanent magnet material is, in mass percent: al: 0-3, Cu: 0-0.5, Co: 0-6, Nb: 0 to 0.3, Zr: 0-0.3, Ga: 0-0.3.
7. The mixed rare earth permanent magnet material according to claims 1-6, wherein B in BC accounts for more than 85% of BC by mass percent.
8. A method for preparing a mixed rare earth permanent magnetic material according to claim 1, comprising:
(1) preparing materials: weighing and batching different elements according to material components, wherein:
the MM directly uses Ce-based mixed rare earth alloy; r is pure rare earth alloy with the purity of more than 99 percent, rare earth alloy containing more than two rare earths or rare earth-iron alloy; m is pure metal or alloy with Fe; b in BC is ferroboron;
(2) alloying: preparing the prepared raw materials into a rapid hardening sheet alloy through a smelting-rapid hardening process or preparing an ingot casting alloy through a smelting-casting process;
(3) crushing: for the quick-setting slices, crushing is directly carried out by using a hydrogen crushing and airflow milling process; for the ingot casting alloy, firstly carrying out rough crushing, then crushing by using a hydrogen crushing and airflow milling process, and crushing the ingot casting alloy into particles; wherein, the hydrogen residual content of the powder after hydrogen breaking is 0.001 to 0.1 percent; after the jet milling process, the oxygen content of the final powder component is 0.01-0.2%;
(4) molding: placing the crushed alloy powder into a die, pressing and molding in a magnetic field of more than 1.5T, and further densifying by cold isostatic pressing to prepare the alloy powder with the density of 3.5-4.5g/cm3A green compact of (1);
(5) and (3) sintering: putting the pressed compact into a metal or graphite material box, and then putting the pressed compact into a sintering furnace to be sintered into a high-density sintered blank; sintering temperature: 1020 ℃ and 1120 ℃, sintering time: 2-5 hours, and before the sintering temperature is reached, the process of temperature rise and heat preservation is carried out in sections;
(6) tempering: and performing primary or secondary tempering on the sintered blank to prepare the mixed rare earth permanent magnetic material with optimized microstructure.
9. The preparation method according to claim 8, wherein the melting-rapid solidification process in (2) comprises placing the prepared raw materials in a crucible, fully melting in a vacuum high-frequency induction furnace, charging argon gas under a certain pressure into the furnace, pouring molten metal liquid onto the surface of a rotating water-cooled copper roller through a tundish, controlling the linear velocity of the surface of the copper roller at 1-3m/s, and rapidly throwing the molten metal from the copper roller to form a rapid solidification sheet with the thickness of 0.1-0.6 mm.
10. The production method according to claim 9, wherein in the step (6),
when the secondary tempering process is adopted, the primary tempering temperature is 850-930 ℃, and the secondary tempering temperature is 400-600 ℃;
when the primary tempering process is adopted, the tempering temperature is 400-650 ℃.
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